It is very important to measure the length of fiber in polymers. Typically when analyzing a sample of fibers many of the individual fibers will overlap one another, making it difficult to determine which fiber termini belong to the same fiber and therefore difficult to confidently measure the lengths of individual fibers.
Confocal laser microscopes have the ability to analyze a microscopy sample in two-dimensions, but also to analyze a third dimension of depth, or distance between the sample and the microscope. In particular, a confocal laser microscope will give a differing signal intensity based on sample depth.